1. Field of the Invention
The present invention relates to an encapsulating sheet, a producing method thereof, a light emitting diode device, and a producing method thereof, to be specific, to a light emitting diode device used for optical use, a producing method thereof, an encapsulating sheet used therein, and a producing method thereof.
2. Description of Related Art
In a light emitting diode device capable of emitting high-energy light, for example, an LED (a light emitting diode element) and an encapsulating layer which encapsulates the LED are provided. In the light emitting diode device, light emitted from the LED transmits through the encapsulating layer.
The LED emits light with high directivity, so that the LED serves as a point light source. That is, a difference in brightness between an immediate upper portion of the LED and a portion around the immediate upper portion thereof becomes greater. Then, color unevenness of the light occurs in the light emitting diode device.
To suppress the occurrence of the color unevenness, for example, a light emitting diode device which includes a light emitting diode chip, a transparent layer encapsulating the light emitting diode chip, and a light scattering layer formed on the upper surface of the transparent layer has been proposed (ref: for example, Japanese Unexamined Patent Publication No. 2007-67204).
The light emitting diode device in Japanese Unexamined Patent Publication No. 2007-67204 is obtained in such a way that the light emitting diode chip is encapsulated by the transparent layer and then, the light scattering layer is disposed on the upper surface of the transparent layer so as to include the light emitting diode chip when projected in the up-down direction.
In the light emitting diode device in Japanese Unexamined Patent Publication No. 2007-67204, after light emitted from the light emitting diode chip upwardly transmits through the transparent layer, the light is scattered in the light scattering layer along the plane direction thereof. Therefore, the light emitting diode chip serves as a surface light source in the light emitting diode device. That is, in the light scattering layer, a difference in brightness between an immediate upper portion of the light emitting diode chip and a portion around the immediate upper portion thereof is reduced. Then, the occurrence of the color unevenness of the light in the light emitting diode device is suppressed.